Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient ...Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure, lithology, porosity, permeability and mineral components all affect the potential for formation damage. The experimental results showed that the permeability loss was 83.8%-98.6% caused by stress sensitivity, and was 27.9%-48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows: the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide (MMH) drilling fluid system was developed, which was mainly composed of low-fluorescence shale control agent, filtration control agent, lowfluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability (over 85%) of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate (API filtration less than 5 ml after aging at 120 ℃ for 4 hours). Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid. Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.展开更多
Pancreatic trauma as a challenge before and during explorative laparotomy is associated with multiple visceral injuries or critical conditions. Its optimal management remains controversial.The current concept of damag...Pancreatic trauma as a challenge before and during explorative laparotomy is associated with multiple visceral injuries or critical conditions. Its optimal management remains controversial.The current concept of damage control surgery (DCS) has been increasingly accepted. DCS展开更多
BACKGROUND The management of high-grade pancreatic trauma is controversial.AIM To review our single-institution experience on the surgical management of blunt and penetrating pancreatic injuries.METHODS A retrospectiv...BACKGROUND The management of high-grade pancreatic trauma is controversial.AIM To review our single-institution experience on the surgical management of blunt and penetrating pancreatic injuries.METHODS A retrospective review of records was performed on all patients undergoing surgical intervention for high-grade pancreatic injuries [American Association for the Surgery of Trauma(AAST) Grade Ⅲor greater] at the Royal North Shore Hospital in Sydney between January 2001 and December 2022. Morbidity and mortality outcomes were reviewed, and major diagnostic and operative challenges were identified.RESULTS Over a twenty-year period, 14 patients underwent pancreatic resection for highgrade injuries. Seven patients sustained AAST Grade Ⅲinjuries and 7 were classified as Grades Ⅳ or Ⅴ. Nine underwent distal pancreatectomy and 5 underwent pancreaticoduodenectomy(PD). Overall, there was a predominance of blunt aetiologies(11/14). Concomitant intra-abdominal injuries were observed in 11 patients and traumatic haemorrhage in 6 patients. Three patients developed clinically relevant pancreatic fistulas and there was one in-hospital mortality secondary to multi-organ failure. Among stable presentations, pancreatic ductal injuries were missed in two-thirds of cases(7/12) on initial computed tomography imaging and subsequently diagnosed on repeat imaging or endoscopic retrograde cholangiopancreatography. All patients who sustained complex pancreaticoduodenal trauma underwent PD without mortality. The management of pancreatic trauma is evolving. Our experience provides valuable and locally relevant insights into future management strategies.CONCLUSION We advocate that high-grade pancreatic trauma should be managed in high-volume hepatopancreato-biliary specialty surgical units. Pancreatic resections including PD may be indicated and safely performed with appropriate specialist surgical, gastroenterology, and interventional radiology support in tertiary centres.展开更多
BACKGROUND The concept of mandatory laparotomy in treating traumatic peritonitis has been increasingly questioned recently.AIM To summarize and share the experience of conservative treatment of patients with multi-tra...BACKGROUND The concept of mandatory laparotomy in treating traumatic peritonitis has been increasingly questioned recently.AIM To summarize and share the experience of conservative treatment of patients with multi-trauma induced peritonitis.METHODS A retrospective review was performed on patients with multiple injury induced traumatic peritonitis.RESULTS A total of 184 patients with multiple injury induced traumatic peritonitis were reviewed.46 of them underwent conservative treatment.None of the 46 patients with conservative treatment switched to surgical treatment,and all of them were cured and discharged after successful conservative treatment.No significant abnormal findings were observed at regular follow-up after discharge.CONCLUSION Conservative management is safe,effective,feasible,and beneficial in hemodynamically stable patients with traumatic peritonitis if there is no definite evidence of severe abdominal visceral organ injury.展开更多
Chinese farmers are often accused of overusing pesticides that play a crucial role in enhancing crop yield by reducing losses to crop pests. Pesticide overuse has caused a series of negative health and environmental e...Chinese farmers are often accused of overusing pesticides that play a crucial role in enhancing crop yield by reducing losses to crop pests. Pesticide overuse has caused a series of negative health and environmental externalities. This paper quantiifes the productivity effect and the optimal amount of pesticides in rice, cotton and maize production in China from the economic perspective. Using survey data col ected in 2012 and 2013, both Cobb-Douglas and Weibul damage control speciifcations are used to estimate the production function. Results show that pesticides have statistical y signiifcant pro-ductivity effect on crop yield. On the condition of Weibul damage control speciifcations, the marginal products of 1 kg of the active ingredients of pesticides for rice, cotton and maize are 71.06, 22.73 and 98.45 kg, respectively. However, 57, 64 and 17%of the actual amount of pesticides are overused for rice, cotton and maize, respectively. Moreover, the productivity effect of pesticides would be overestimated using Cobb-Douglas speciifcation without incorporating a damage control agent.展开更多
BACKGROUND: Recurrence of inflammation in the extrahepatic bile duct can lead to bile duct stenosis' obstructive jaundice and cavernous transformation of the portal vein. The latter can develop into extrahepatic p...BACKGROUND: Recurrence of inflammation in the extrahepatic bile duct can lead to bile duct stenosis' obstructive jaundice and cavernous transformation of the portal vein. The latter can develop into extrahepatic portal hypertension (PHT). It is difficult to establish the correct method for treating these conditions. METHODS: At another hospital, a 51-year-old man developed PHT as a result of endoscopic retrograde cholangiopancreatography and endoscopic nasobiliary drainage to relieve cholelithiasis and obstructive jaundice. We dealt with the biliary tract obstruction through percutaneous transhepatic cholangial drainage (PTCD), followed by selective devascularization and a shunt operation 2 weeks after the disappearance of jaundice. Three months after cholecystojejunostomy, there were no obvious changes around the bile duct. RESULT: The patient recovered uneventfully and was discharged 14 days after operation. CONCLUSION: For this patient, surgery in stages was the best choice. The most suitable method to decrease jaundice is PTCD.展开更多
BACKGROUND: Portal hypertension is one of the most im- portant clinical conditions that cause intraoperative intensive hemorrhage in cirrhotic patients undergoing liver transplan- tation. Pre-transplant portal decomp...BACKGROUND: Portal hypertension is one of the most im- portant clinical conditions that cause intraoperative intensive hemorrhage in cirrhotic patients undergoing liver transplan- tation. Pre-transplant portal decompression may reduce the intraoperative bleeding during liver transplantation.展开更多
A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yus...A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.展开更多
Pancreatic trauma is rare compared to other abdominal solid organ injuries,accounting for 0.2%-0.3% of all trauma patients. Moreover, this type of injury may frequently be overlooked or not readily appreciated on init...Pancreatic trauma is rare compared to other abdominal solid organ injuries,accounting for 0.2%-0.3% of all trauma patients. Moreover, this type of injury may frequently be overlooked or not readily appreciated on initial clinical examinations and investigations. The organ injury scale determines the severity of the trauma. Nonetheless, there are conflicting recommendations for the best strategy in severe cases. Overall, conservative management of induced severe traumatic pancreatitis is adequate. Modern imaging modalities such as ultrasound scanning and computed tomography scanning can detect injuries in fewer than 60% of patients. However, magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography(ERCP) have diagnostic accuracies approaching 90%-100%. Thus, management options include ERCP and stent placement or distal pancreatectomy in cases of complete gland transection and wide drainage only for damage control surgery, which can prevent mortality but increases the risk of morbidity. In the majority of cases, surgical intervention is not required and should be reserved for only severe grade Ⅲ to grade Ⅴ injuries.展开更多
Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams' rule has been used for this purpose. However, Abrams' rule only addresses the ...Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams' rule has been used for this purpose. However, Abrams' rule only addresses the size of particle required to initiate a bridge. The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing. This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes, especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations, compared with the conventionally used techniques. Practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper. A carefully designed drill-in fluid by using the ideal packing technique (named the IPT fluid) for offshore drilling operations at the Weizhou Oilfield, Nanhai West Company, CNOOC is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.展开更多
A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolu...A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolution in fracture plugging zone to reveal the evolution mechanism of the structure of fracture plugging zone.A theoretical basis is provided for improving the lost circulation control effect in fractured reservoirs and novel methods are proposed for selecting loss control materials and designing loss control formula.CFD-DEM simulation results show that bridging probability is the key factor determining the formation of fracture plugging zone and fracture plugging efficiency.Critical and absolute bridging concentrations are proposed as the key indexes for loss control formula design.With the increase of absolute bridging concentration,the governing factor of bridging is changed from material grain size to the combination of material grain size and friction force.Results of photo-elastic experiments show that mesoscale force chain network is the intrinsic factor affecting the evolution of pressure exerting on the fracture plugging zone and determines the macroscopic strength of fracture plugging zone.Performance parameters of loss control material affect the force chain network structure and the ratio of stronger force chain,and further impact the stability and strength of fracture plugging zone.Based on the study results,the loss control formula is optimized and new-type loss control material is designed.Laboratory experiments results show that the fracture plugging efficiency and strength is effectively improved.展开更多
BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The ...BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The OB Critical Assessment Team(OBCAT Alert) was developed at our institution to facilitate a multidisciplinary response to complex OB/GYN cases.We sought to review and characterize the Acute Care/Trauma Surgeon's role in these cases.METHODS:We conducted a retrospective review of all emergency consults during an OB/GYN case at our institution from 2008 to 2015.An OBCAT is a hospital based alert system designed to immediately notify OB/GYN,anesthesiology,Acute Care/Trauma,the intensive care unit(ICU),and the blood bank of a potential emergency during an OB/GYN case.RESULTS:There were 7±3 OBCAT alerts/year.Seventeen patients required Acute Care/Trauma surgery intervention for hemorrhage.Thirteen patients required damage control packing during their hospitalization.Blood loss averaged 6.8±5.5 L and patients received a total of 21±14units during deliveries with hemorrhage.There were 17 other surgical interventions not related to hemorrhage;seven of these cases were related to adhesions or intestinal injury.Seven additional cases required evaluation post routine OB/GYN procedure;the most common reason was for severe wound complications.There were three deaths during this study period.CONCLUSION:Emergency OB/GYN cases are associated with high morbidity and may require damage control or other surgical techniques in cases of overwhelming hemorrhage.Acute Care/Trauma Surgeons have a key role in the treatment of these complex cases.展开更多
Objective and Methods Insecticide use, grower preferences regarding genetically engineered (GE) corn resistant to com rootworm (CRW), and the health effects of using various CRW insecticides (organophosphates, pyrethr...Objective and Methods Insecticide use, grower preferences regarding genetically engineered (GE) corn resistant to com rootworm (CRW), and the health effects of using various CRW insecticides (organophosphates, pyrethroids, fipronil and carbamates) are reviewed for current and future farm practices. Results Pest damage to corn has been reduced only one-third by insecticide applications. Health costs from insecticide use appear significant, but costs attributable to CRW control are not quantifiable from available data. Methods reducing health-related costs of insecticide-based CRW control should be evaluated. As a first step, organophosphate insecticide use has been reduced as they have high acute toxicity and risk of long-term neurological consequences. A second step is to use agents which more specifically target the CRW. Conclusion Whereas current insecticides may be poisonous to many species of insects, birds, mammals and humans, a protein derived from Bacillus thurigiensis and produced in plants via genetic modification can target the specific insect of CRW (Coleoptra), sparing other insect and non-insect species from injury.展开更多
BACKGROUND In recent years,we created and employed a new anastomosis method,“bridging”pancreaticogastrostomy,to treat patients with extremely severe pancreatic injury.This surgery has advantages such as short length...BACKGROUND In recent years,we created and employed a new anastomosis method,“bridging”pancreaticogastrostomy,to treat patients with extremely severe pancreatic injury.This surgery has advantages such as short length of surgery,low secondary trauma,rapid construction of shunts for pancreatic fluid,preventing second surgeries,and achieving good treatment outcomes in clinical practice.However,due to the limited number of clinical cases,there is a lack of strong evidence to support the feasibility and safety of this surgical procedure.Therefore,we carried out animal experiments to examine this procedure,which is reported here.AIM To examine the feasibility and safety of a new rapid method of pancreaticogastrostomy,“bridging”pancreaticogastrostomy.METHODS Ten Landrace pigs were randomized into the experimental and control groups,with five pigs in each group.“Bridging”pancreaticogastrostomy was performed in the experimental group,while routine mucosa-to-mucosa pancreaticogastrostomy was performed in the control group.After surgery,the general condition,amylase levels in drainage fluid on Days 1,3,5,and 7,fasting and 2-h postprandial blood glucose 6 mo after surgery,fasting,2-h postprandial peripheral blood insulin,and portal vein blood insulin 6 mo after surgery were assessed.Resurgery was carried out at 1 and 6 mo after the former one to examine the condition of the abdominal cavity and firmness and tightness of the pancreaticogastric anastomosis and pancreas.RESULTS After surgery,the general condition of the animals was good.One in the control group did not gain weight 6 mo after surgery,whereas significant weight gain was present in the others.There were significant differences on Days 1 and 3 after surgery between the two groups but no differences on Days 5 and 7.There were no differences in fasting and 2-h postprandial blood glucose and fasting and 2-h insulin values of postprandial peripheral blood and portal vein blood 6 mo after surgery between the two groups.One month after surgery,the sinus tract orifice/anastomosis was patent in the two groups.Six months after surgery,the sinus tract orifice/anastomosis was sealed,and pancreases in both groups presented with chronic pancreatitis.CONCLUSION“Bridging”pancreaticogastrostomy is a feasible and safe a means of damage control surgery during the early stage of pancreatic injury.展开更多
Multiple segmental fractures of the lower limbs, common in developing countries, are the prerogative of Road Traffic Accidents (RTA) involving two-wheeled vehicles. Their management is difficult, associated with compl...Multiple segmental fractures of the lower limbs, common in developing countries, are the prerogative of Road Traffic Accidents (RTA) involving two-wheeled vehicles. Their management is difficult, associated with complications, and is most often based on a two-stage strategy: Damage Control Orthopaedics, followed by delayed internal osteosynthesis. The aim is to allow early functional rehabilitation and rapid recovery of patients. We report the case of a 39-year-old man, bike rider, after his RTA, presented with segmental homolateral fractures of the femur and two bones of the left leg. Short-term evolution was marked by the appearance of significant lymphedema and bone infarctions of the lower left limb necessitating a transfemoral amputation. Through this observation, the authors highlight the problems related to the complexity of the management of multiple segmental fractures of the lower limb by emphasizing two post-traumatic complications rarely described but to be feared: chronic lymphedema and bone infarction.展开更多
The recent implementation of trauma-validated damage control strategies in severe postpartum hemorrhage proves the importance of interdisciplinary management in the obstetric patient.Massive hemorrhage control techniq...The recent implementation of trauma-validated damage control strategies in severe postpartum hemorrhage proves the importance of interdisciplinary management in the obstetric patient.Massive hemorrhage control techniques and damage control surgery are clear examples of how learning from trauma can benefit the obstetric population.Currently,most obstetric programs do not include training in this type of interventions.Nevertheless,it has been shown that these interventions are useful in the management of severe postpartum hemorrhage.The aim of this article is to introduce the application of damage control surgery principles in the management of massive obstetric hemorrhage.We propose to include appropriate training and the implementation of damage control surgery in obstetric management protocols.The prompt application of damage control principles can be considered in patients with persistent hemodynamic instability despite control of the source of bleeding.展开更多
The diagnosis and treatment of pelvic ring disruption has significantly changed over the past 30 years.It was not until the 1980s that the concept of damage control surgery was applied in the management of severely tr...The diagnosis and treatment of pelvic ring disruption has significantly changed over the past 30 years.It was not until the 1980s that the concept of damage control surgery was applied in the management of severely traumatized patients.The contents of damage control surgery mainly include three phases:the initial stage,the goal of severe pelvic trauma treatment is using simple surgical techniques to control life-threatening bleeding;the second stage,the physiological disturbances of the patients were corrected by ICU resuscitation;and the third stage,the definitive surgery performed for the injuries.1 About 10% to 20% of patients with severe unstable pelvic fracture also present with hemodynamic instability,and the mortality rate of them can be as high as 40%.2-4 Although hemodynamic resuscitation techniques have made great progress,some patients do not respond or poorly respond to resuscitation treatment.展开更多
With the advent of global aging,the incidence,mortality,and medical costs of hip fracture among aged patients are increasing annually.The number of controlled clinical studies and health economics analyses that confor...With the advent of global aging,the incidence,mortality,and medical costs of hip fracture among aged patients are increasing annually.The number of controlled clinical studies and health economics analyses that conform to evidence-based medicine principles is growing day by day.However,unfortunately,no specific recommendations regarding the procedures for the treatment of hip fracture are available.Meanwhile,the existence of both traditional treatment systems and new treatment theories means that most doctors confront difficult choices in their daily practice.These factors make the therapeutic approach for aged patients,especially among superaged patients with hip fracture,extremely challenging.This study focuses on superaged patients(>80 years as defined by the World Health Organization)with hip fracture and includes their preoperative pathological condition;therapeutic decision-making in terms of the benefit and risk ratio,damage control theory,and enhanced recovery after surgery were also investigated.These patients were discussed specifically by combining the current treatment strategies from several experts and the results of a meta-analysis published recently.The study presents some new ideas and approaches currently recognized in the field,such as preoperative assessment,surgical planning,safety consideration,complication intervention,and enhanced recovery implementation,and further presents some clear interpretations regarding misunderstandings in clinical practice.Finally,optimized treatment according to damage control principles and enhanced recovery after surgery during the perioperative period among superaged hip fracture patients is defined.展开更多
Objective: To investigate the application of damage control surgery in treatment of patients with severe thoracic and abdominal injuries.Methods: A retrospective study was done on 37 patients with severe thoracic and ...Objective: To investigate the application of damage control surgery in treatment of patients with severe thoracic and abdominal injuries.Methods: A retrospective study was done on 37 patients with severe thoracic and abdominal injuries who underwent damage control surgery from January 2000 to October 2006 in our department. There were 8 cases of polytrauma ( with thoracic injury most commonly seen), 21 of polytrauma (with abdominal injury most commonly seen) and 8 of single abdominal trauma. Main organ damage included smashed hepatic injuries in 17 cases,posterior hepatic veins injuries in 8, pancreaticoduodenal injuries in 7, epidural or subdural hemorrhage in 4,contusion and laceration of brain in 5, severe lung and bronchus injuries in 4, pelvis and one smashed lower limb wound in 3 and pelvic fractures and retroperitoneal hemorrhage in 6. Injury severity score (ISS) was 28-45 scores (38.4 scores on average), abbreviated injury scale (ALS) ≥ 4.13. The patients underwent arteriography and arterial embolization including arteria hepatica embolization in 4 patients, arteria renalis embolization in 2 and pelvic arteria retroperitoneal embolization in 7. Once abbreviated operation finished, the patients were sent to ICU for resuscitation. Twenty-four cases underwent definitive operation within 48 hours after initial operation, 5 underwent definitive operation within 72 hours after initial operation, 2 cases underwent definitive operation postponed to 96 hours after initial operation for secondary operation to control bleeding because of abdominal cavity hemorrhea.Two cases underwent urgent laparotomy and decompression because of abdominal compartment syndrome and 2 cases underwent secondary operation because of intestinal fistulae (1 case of small intestinal fistula and 1 colon fistula) and gangrene of gallbladder.Results: A total of 28 patients survived, with a survival rate of 75.68%, and 9 died (4 died within 24 hours and 5 died 3-9 days after injury). The trauma deaths at the early stage were caused by severe primary injuries resulting in failure of respiration and circulation, while mortality at the later stage was caused by multiple organ failure.Conclusions: Damage control surgery is important for the treatment against severe thoracic and abdominal injuries. It is suggested that the surgeon should select the reasonable auxiliary examination before operation, and take the proper time to perform damage control and definitive surgery.展开更多
The objective of the present study is to analytically investigate temperature effects of an axial-type seismic damper made of shape memory alloys(SMAs)equipped in steel frames.Based on a modified multilinear one dimen...The objective of the present study is to analytically investigate temperature effects of an axial-type seismic damper made of shape memory alloys(SMAs)equipped in steel frames.Based on a modified multilinear one dimensional constitutive model of SMAs,two types of SMAs are employed,which have different stress plateau and different stress growth rate with temperature increase.Temperature effects of SMA dampers on seismic performance upgrading are discussed in three aspects:different environment temperatures;rapid loading rate induced heat generation and different SMA fractions.The analysis indicates that the effect of environment temperature should be considered for the SMA damper in steel frames.However,the rapid loading rate induced heat generation has little adverse effect.展开更多
基金the National Natural Science Foundation of China(No.50574061)
文摘Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure, lithology, porosity, permeability and mineral components all affect the potential for formation damage. The experimental results showed that the permeability loss was 83.8%-98.6% caused by stress sensitivity, and was 27.9%-48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows: the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide (MMH) drilling fluid system was developed, which was mainly composed of low-fluorescence shale control agent, filtration control agent, lowfluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability (over 85%) of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate (API filtration less than 5 ml after aging at 120 ℃ for 4 hours). Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid. Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.
基金The study is supported by a grant from special project of Chinese Military Medicine Science and Technology Research "11.5" plan (No. 06Z017).
文摘Pancreatic trauma as a challenge before and during explorative laparotomy is associated with multiple visceral injuries or critical conditions. Its optimal management remains controversial.The current concept of damage control surgery (DCS) has been increasingly accepted. DCS
基金Research protocol was approved by the Northern Sydney Local Health District ethics committee as a negligible/Low risk project.This study was not a trial or animal study.
文摘BACKGROUND The management of high-grade pancreatic trauma is controversial.AIM To review our single-institution experience on the surgical management of blunt and penetrating pancreatic injuries.METHODS A retrospective review of records was performed on all patients undergoing surgical intervention for high-grade pancreatic injuries [American Association for the Surgery of Trauma(AAST) Grade Ⅲor greater] at the Royal North Shore Hospital in Sydney between January 2001 and December 2022. Morbidity and mortality outcomes were reviewed, and major diagnostic and operative challenges were identified.RESULTS Over a twenty-year period, 14 patients underwent pancreatic resection for highgrade injuries. Seven patients sustained AAST Grade Ⅲinjuries and 7 were classified as Grades Ⅳ or Ⅴ. Nine underwent distal pancreatectomy and 5 underwent pancreaticoduodenectomy(PD). Overall, there was a predominance of blunt aetiologies(11/14). Concomitant intra-abdominal injuries were observed in 11 patients and traumatic haemorrhage in 6 patients. Three patients developed clinically relevant pancreatic fistulas and there was one in-hospital mortality secondary to multi-organ failure. Among stable presentations, pancreatic ductal injuries were missed in two-thirds of cases(7/12) on initial computed tomography imaging and subsequently diagnosed on repeat imaging or endoscopic retrograde cholangiopancreatography. All patients who sustained complex pancreaticoduodenal trauma underwent PD without mortality. The management of pancreatic trauma is evolving. Our experience provides valuable and locally relevant insights into future management strategies.CONCLUSION We advocate that high-grade pancreatic trauma should be managed in high-volume hepatopancreato-biliary specialty surgical units. Pancreatic resections including PD may be indicated and safely performed with appropriate specialist surgical, gastroenterology, and interventional radiology support in tertiary centres.
文摘BACKGROUND The concept of mandatory laparotomy in treating traumatic peritonitis has been increasingly questioned recently.AIM To summarize and share the experience of conservative treatment of patients with multi-trauma induced peritonitis.METHODS A retrospective review was performed on patients with multiple injury induced traumatic peritonitis.RESULTS A total of 184 patients with multiple injury induced traumatic peritonitis were reviewed.46 of them underwent conservative treatment.None of the 46 patients with conservative treatment switched to surgical treatment,and all of them were cured and discharged after successful conservative treatment.No significant abnormal findings were observed at regular follow-up after discharge.CONCLUSION Conservative management is safe,effective,feasible,and beneficial in hemodynamically stable patients with traumatic peritonitis if there is no definite evidence of severe abdominal visceral organ injury.
基金financial support from the National Natural Science Foundation of China (71173014 and 71210004)the China Scholarship Council (201306030053)
文摘Chinese farmers are often accused of overusing pesticides that play a crucial role in enhancing crop yield by reducing losses to crop pests. Pesticide overuse has caused a series of negative health and environmental externalities. This paper quantiifes the productivity effect and the optimal amount of pesticides in rice, cotton and maize production in China from the economic perspective. Using survey data col ected in 2012 and 2013, both Cobb-Douglas and Weibul damage control speciifcations are used to estimate the production function. Results show that pesticides have statistical y signiifcant pro-ductivity effect on crop yield. On the condition of Weibul damage control speciifcations, the marginal products of 1 kg of the active ingredients of pesticides for rice, cotton and maize are 71.06, 22.73 and 98.45 kg, respectively. However, 57, 64 and 17%of the actual amount of pesticides are overused for rice, cotton and maize, respectively. Moreover, the productivity effect of pesticides would be overestimated using Cobb-Douglas speciifcation without incorporating a damage control agent.
文摘BACKGROUND: Recurrence of inflammation in the extrahepatic bile duct can lead to bile duct stenosis' obstructive jaundice and cavernous transformation of the portal vein. The latter can develop into extrahepatic portal hypertension (PHT). It is difficult to establish the correct method for treating these conditions. METHODS: At another hospital, a 51-year-old man developed PHT as a result of endoscopic retrograde cholangiopancreatography and endoscopic nasobiliary drainage to relieve cholelithiasis and obstructive jaundice. We dealt with the biliary tract obstruction through percutaneous transhepatic cholangial drainage (PTCD), followed by selective devascularization and a shunt operation 2 weeks after the disappearance of jaundice. Three months after cholecystojejunostomy, there were no obvious changes around the bile duct. RESULT: The patient recovered uneventfully and was discharged 14 days after operation. CONCLUSION: For this patient, surgery in stages was the best choice. The most suitable method to decrease jaundice is PTCD.
文摘BACKGROUND: Portal hypertension is one of the most im- portant clinical conditions that cause intraoperative intensive hemorrhage in cirrhotic patients undergoing liver transplan- tation. Pre-transplant portal decompression may reduce the intraoperative bleeding during liver transplantation.
基金Special Fund for Earthquake Research under Grant No.201208013National key Technology R&D Program under Grant No.2012BAK15B05Basic Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2010A04
文摘A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.
文摘Pancreatic trauma is rare compared to other abdominal solid organ injuries,accounting for 0.2%-0.3% of all trauma patients. Moreover, this type of injury may frequently be overlooked or not readily appreciated on initial clinical examinations and investigations. The organ injury scale determines the severity of the trauma. Nonetheless, there are conflicting recommendations for the best strategy in severe cases. Overall, conservative management of induced severe traumatic pancreatitis is adequate. Modern imaging modalities such as ultrasound scanning and computed tomography scanning can detect injuries in fewer than 60% of patients. However, magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography(ERCP) have diagnostic accuracies approaching 90%-100%. Thus, management options include ERCP and stent placement or distal pancreatectomy in cases of complete gland transection and wide drainage only for damage control surgery, which can prevent mortality but increases the risk of morbidity. In the majority of cases, surgical intervention is not required and should be reserved for only severe grade Ⅲ to grade Ⅴ injuries.
基金supported by the National Natural Science Foundation(Project No.50574061)the Changjiang Scholars and Innovative Research Team(No.IRT0411),Ministry of Education
文摘Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams' rule has been used for this purpose. However, Abrams' rule only addresses the size of particle required to initiate a bridge. The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing. This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes, especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations, compared with the conventionally used techniques. Practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper. A carefully designed drill-in fluid by using the ideal packing technique (named the IPT fluid) for offshore drilling operations at the Weizhou Oilfield, Nanhai West Company, CNOOC is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.
基金Supported by the National Natural Science Foundation of China(51604236)Open Fund of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201913)+1 种基金Science and Technology Planning Project of the Sichuan Province,China(2018JY0436)Sichuan Youth Science and Technology Innovation Research Team Project for Unconventional Oil and Gas Reservoir Protection(2016TD0016)。
文摘A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolution in fracture plugging zone to reveal the evolution mechanism of the structure of fracture plugging zone.A theoretical basis is provided for improving the lost circulation control effect in fractured reservoirs and novel methods are proposed for selecting loss control materials and designing loss control formula.CFD-DEM simulation results show that bridging probability is the key factor determining the formation of fracture plugging zone and fracture plugging efficiency.Critical and absolute bridging concentrations are proposed as the key indexes for loss control formula design.With the increase of absolute bridging concentration,the governing factor of bridging is changed from material grain size to the combination of material grain size and friction force.Results of photo-elastic experiments show that mesoscale force chain network is the intrinsic factor affecting the evolution of pressure exerting on the fracture plugging zone and determines the macroscopic strength of fracture plugging zone.Performance parameters of loss control material affect the force chain network structure and the ratio of stronger force chain,and further impact the stability and strength of fracture plugging zone.Based on the study results,the loss control formula is optimized and new-type loss control material is designed.Laboratory experiments results show that the fracture plugging efficiency and strength is effectively improved.
文摘BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The OB Critical Assessment Team(OBCAT Alert) was developed at our institution to facilitate a multidisciplinary response to complex OB/GYN cases.We sought to review and characterize the Acute Care/Trauma Surgeon's role in these cases.METHODS:We conducted a retrospective review of all emergency consults during an OB/GYN case at our institution from 2008 to 2015.An OBCAT is a hospital based alert system designed to immediately notify OB/GYN,anesthesiology,Acute Care/Trauma,the intensive care unit(ICU),and the blood bank of a potential emergency during an OB/GYN case.RESULTS:There were 7±3 OBCAT alerts/year.Seventeen patients required Acute Care/Trauma surgery intervention for hemorrhage.Thirteen patients required damage control packing during their hospitalization.Blood loss averaged 6.8±5.5 L and patients received a total of 21±14units during deliveries with hemorrhage.There were 17 other surgical interventions not related to hemorrhage;seven of these cases were related to adhesions or intestinal injury.Seven additional cases required evaluation post routine OB/GYN procedure;the most common reason was for severe wound complications.There were three deaths during this study period.CONCLUSION:Emergency OB/GYN cases are associated with high morbidity and may require damage control or other surgical techniques in cases of overwhelming hemorrhage.Acute Care/Trauma Surgeons have a key role in the treatment of these complex cases.
文摘Objective and Methods Insecticide use, grower preferences regarding genetically engineered (GE) corn resistant to com rootworm (CRW), and the health effects of using various CRW insecticides (organophosphates, pyrethroids, fipronil and carbamates) are reviewed for current and future farm practices. Results Pest damage to corn has been reduced only one-third by insecticide applications. Health costs from insecticide use appear significant, but costs attributable to CRW control are not quantifiable from available data. Methods reducing health-related costs of insecticide-based CRW control should be evaluated. As a first step, organophosphate insecticide use has been reduced as they have high acute toxicity and risk of long-term neurological consequences. A second step is to use agents which more specifically target the CRW. Conclusion Whereas current insecticides may be poisonous to many species of insects, birds, mammals and humans, a protein derived from Bacillus thurigiensis and produced in plants via genetic modification can target the specific insect of CRW (Coleoptra), sparing other insect and non-insect species from injury.
文摘BACKGROUND In recent years,we created and employed a new anastomosis method,“bridging”pancreaticogastrostomy,to treat patients with extremely severe pancreatic injury.This surgery has advantages such as short length of surgery,low secondary trauma,rapid construction of shunts for pancreatic fluid,preventing second surgeries,and achieving good treatment outcomes in clinical practice.However,due to the limited number of clinical cases,there is a lack of strong evidence to support the feasibility and safety of this surgical procedure.Therefore,we carried out animal experiments to examine this procedure,which is reported here.AIM To examine the feasibility and safety of a new rapid method of pancreaticogastrostomy,“bridging”pancreaticogastrostomy.METHODS Ten Landrace pigs were randomized into the experimental and control groups,with five pigs in each group.“Bridging”pancreaticogastrostomy was performed in the experimental group,while routine mucosa-to-mucosa pancreaticogastrostomy was performed in the control group.After surgery,the general condition,amylase levels in drainage fluid on Days 1,3,5,and 7,fasting and 2-h postprandial blood glucose 6 mo after surgery,fasting,2-h postprandial peripheral blood insulin,and portal vein blood insulin 6 mo after surgery were assessed.Resurgery was carried out at 1 and 6 mo after the former one to examine the condition of the abdominal cavity and firmness and tightness of the pancreaticogastric anastomosis and pancreas.RESULTS After surgery,the general condition of the animals was good.One in the control group did not gain weight 6 mo after surgery,whereas significant weight gain was present in the others.There were significant differences on Days 1 and 3 after surgery between the two groups but no differences on Days 5 and 7.There were no differences in fasting and 2-h postprandial blood glucose and fasting and 2-h insulin values of postprandial peripheral blood and portal vein blood 6 mo after surgery between the two groups.One month after surgery,the sinus tract orifice/anastomosis was patent in the two groups.Six months after surgery,the sinus tract orifice/anastomosis was sealed,and pancreases in both groups presented with chronic pancreatitis.CONCLUSION“Bridging”pancreaticogastrostomy is a feasible and safe a means of damage control surgery during the early stage of pancreatic injury.
文摘Multiple segmental fractures of the lower limbs, common in developing countries, are the prerogative of Road Traffic Accidents (RTA) involving two-wheeled vehicles. Their management is difficult, associated with complications, and is most often based on a two-stage strategy: Damage Control Orthopaedics, followed by delayed internal osteosynthesis. The aim is to allow early functional rehabilitation and rapid recovery of patients. We report the case of a 39-year-old man, bike rider, after his RTA, presented with segmental homolateral fractures of the femur and two bones of the left leg. Short-term evolution was marked by the appearance of significant lymphedema and bone infarctions of the lower left limb necessitating a transfemoral amputation. Through this observation, the authors highlight the problems related to the complexity of the management of multiple segmental fractures of the lower limb by emphasizing two post-traumatic complications rarely described but to be feared: chronic lymphedema and bone infarction.
文摘The recent implementation of trauma-validated damage control strategies in severe postpartum hemorrhage proves the importance of interdisciplinary management in the obstetric patient.Massive hemorrhage control techniques and damage control surgery are clear examples of how learning from trauma can benefit the obstetric population.Currently,most obstetric programs do not include training in this type of interventions.Nevertheless,it has been shown that these interventions are useful in the management of severe postpartum hemorrhage.The aim of this article is to introduce the application of damage control surgery principles in the management of massive obstetric hemorrhage.We propose to include appropriate training and the implementation of damage control surgery in obstetric management protocols.The prompt application of damage control principles can be considered in patients with persistent hemodynamic instability despite control of the source of bleeding.
文摘The diagnosis and treatment of pelvic ring disruption has significantly changed over the past 30 years.It was not until the 1980s that the concept of damage control surgery was applied in the management of severely traumatized patients.The contents of damage control surgery mainly include three phases:the initial stage,the goal of severe pelvic trauma treatment is using simple surgical techniques to control life-threatening bleeding;the second stage,the physiological disturbances of the patients were corrected by ICU resuscitation;and the third stage,the definitive surgery performed for the injuries.1 About 10% to 20% of patients with severe unstable pelvic fracture also present with hemodynamic instability,and the mortality rate of them can be as high as 40%.2-4 Although hemodynamic resuscitation techniques have made great progress,some patients do not respond or poorly respond to resuscitation treatment.
基金Clinical research program of Xinqiao Hospital,Amy Medical University(grant no.2015YLC23)Technological Innovation and Application Demonstration Project of Chongqing(cstc2018jscx-msybX0051)。
文摘With the advent of global aging,the incidence,mortality,and medical costs of hip fracture among aged patients are increasing annually.The number of controlled clinical studies and health economics analyses that conform to evidence-based medicine principles is growing day by day.However,unfortunately,no specific recommendations regarding the procedures for the treatment of hip fracture are available.Meanwhile,the existence of both traditional treatment systems and new treatment theories means that most doctors confront difficult choices in their daily practice.These factors make the therapeutic approach for aged patients,especially among superaged patients with hip fracture,extremely challenging.This study focuses on superaged patients(>80 years as defined by the World Health Organization)with hip fracture and includes their preoperative pathological condition;therapeutic decision-making in terms of the benefit and risk ratio,damage control theory,and enhanced recovery after surgery were also investigated.These patients were discussed specifically by combining the current treatment strategies from several experts and the results of a meta-analysis published recently.The study presents some new ideas and approaches currently recognized in the field,such as preoperative assessment,surgical planning,safety consideration,complication intervention,and enhanced recovery implementation,and further presents some clear interpretations regarding misunderstandings in clinical practice.Finally,optimized treatment according to damage control principles and enhanced recovery after surgery during the perioperative period among superaged hip fracture patients is defined.
文摘Objective: To investigate the application of damage control surgery in treatment of patients with severe thoracic and abdominal injuries.Methods: A retrospective study was done on 37 patients with severe thoracic and abdominal injuries who underwent damage control surgery from January 2000 to October 2006 in our department. There were 8 cases of polytrauma ( with thoracic injury most commonly seen), 21 of polytrauma (with abdominal injury most commonly seen) and 8 of single abdominal trauma. Main organ damage included smashed hepatic injuries in 17 cases,posterior hepatic veins injuries in 8, pancreaticoduodenal injuries in 7, epidural or subdural hemorrhage in 4,contusion and laceration of brain in 5, severe lung and bronchus injuries in 4, pelvis and one smashed lower limb wound in 3 and pelvic fractures and retroperitoneal hemorrhage in 6. Injury severity score (ISS) was 28-45 scores (38.4 scores on average), abbreviated injury scale (ALS) ≥ 4.13. The patients underwent arteriography and arterial embolization including arteria hepatica embolization in 4 patients, arteria renalis embolization in 2 and pelvic arteria retroperitoneal embolization in 7. Once abbreviated operation finished, the patients were sent to ICU for resuscitation. Twenty-four cases underwent definitive operation within 48 hours after initial operation, 5 underwent definitive operation within 72 hours after initial operation, 2 cases underwent definitive operation postponed to 96 hours after initial operation for secondary operation to control bleeding because of abdominal cavity hemorrhea.Two cases underwent urgent laparotomy and decompression because of abdominal compartment syndrome and 2 cases underwent secondary operation because of intestinal fistulae (1 case of small intestinal fistula and 1 colon fistula) and gangrene of gallbladder.Results: A total of 28 patients survived, with a survival rate of 75.68%, and 9 died (4 died within 24 hours and 5 died 3-9 days after injury). The trauma deaths at the early stage were caused by severe primary injuries resulting in failure of respiration and circulation, while mortality at the later stage was caused by multiple organ failure.Conclusions: Damage control surgery is important for the treatment against severe thoracic and abdominal injuries. It is suggested that the surgeon should select the reasonable auxiliary examination before operation, and take the proper time to perform damage control and definitive surgery.
基金The study was partially funded by the JSPS Grants-in-Aid for Challenging Exploratory Research(No.23656292)and by grants from Japan Science and Technology Agency for“Evaluation and Mitigation of Environment Impacts of Earthquake and Typhoon Disaster on Urban Area and Infrastructures”(Project Title:Refined Analysis and Damage Control of Earthquake Disaster Impact on Bridge Structures),under the Strategic Japanese-Chinese Cooperative Program on Science and Technology(S&T)for Environmental Conservation and Construction of a Society with Less Environmental Burden.
文摘The objective of the present study is to analytically investigate temperature effects of an axial-type seismic damper made of shape memory alloys(SMAs)equipped in steel frames.Based on a modified multilinear one dimensional constitutive model of SMAs,two types of SMAs are employed,which have different stress plateau and different stress growth rate with temperature increase.Temperature effects of SMA dampers on seismic performance upgrading are discussed in three aspects:different environment temperatures;rapid loading rate induced heat generation and different SMA fractions.The analysis indicates that the effect of environment temperature should be considered for the SMA damper in steel frames.However,the rapid loading rate induced heat generation has little adverse effect.